Bent Axis Pump Pin Bushing for Friction Reduction
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Solution Overview
Problem
Bent axis pumps suffer from premature breakage of the pin due to friction and stress caused by slight shifts between the pin and the central body, despite strengthening the pin with coatings and increased lubrication, which limits its lifespan.
Innovation Solution
A bush with a bimetallic contact portion and an anti-friction coating is inserted between the pin and the seat, providing low friction, damping vibrations, and allowing slight movements to absorb mechanical stresses, thus extending the pin's life and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pin is strengthened through coating materials and increased lubrication, then the friction and stress are reduced, but the pin still breaks prematurely due to slight shifts between the pin and central body
Solution Approach 1:
A bush is introduced as an intermediary element between the pin and the central body seat. The bush comprises a metal portion and a polymer portion, where the polymer portion provides a compliant interface that absorbs slight shifts and misalignments, preventing direct metal-to-metal contact and the resulting stresses that cause pin breakage. This mediator element resolves the contradiction by providing both friction reduction and breakage prevention simultaneously.
Solution Approach 2:
The bush is constructed as a composite structure combining a metal portion (for structural strength and load bearing) and a polymer portion (for friction reduction and compliance). This composite material approach allows the bush to simultaneously provide mechanical support, reduce friction, and absorb misalignment stresses, thereby preventing pin breakage while maintaining reliability under varying operating conditions.
2Reliability
If the pin is made more robust to prevent breakage, then the lifespan is extended, but the friction and mechanical stresses increase
Solution Approach 1:
The bush acts as a mediator that reduces the transmission of mechanical stresses and friction from the pin to the central body. The polymer portion of the bush provides a low-friction interface that reduces harmful frictional forces, while the compliant material absorbs shock and vibration, thereby reducing mechanical stresses without requiring the pin to be more robust.
Solution Approach 2:
The bush changes the material parameters at the critical interface between the pin and central body. By using a polymer material with lower friction coefficients and higher compliance than metal, the bush reduces friction and stress concentrations. This parameter change allows the system to operate with reduced harmful factors while maintaining pin reliability through the bush's protective presence.
3Ease of operation
If coating materials are applied to the pin to reduce friction, then the lubrication requirement is reduced, but the pin still breaks due to stress from slight shifts
Solution Approach 1:
The bush serves as a mediator that provides both friction reduction and stress absorption functions. The polymer portion of the bush provides a low-friction interface, reducing the need for external lubrication, while simultaneously absorbing the stresses from slight shifts between the pin and central body. This single intermediary element thus addresses both the ease of operation requirement and the reliability concern that cannot be resolved by pin coatings alone.
Solution Approach 2:
The composite bush structure combines the low-friction properties of polymer materials with the structural integrity of metal. This composite approach allows the system to operate with reduced lubrication requirements while simultaneously providing the stress absorption needed to prevent pin breakage, resolving the contradiction between ease of operation and reliability.
4Manufacturing precision
If the coupling between pin and central body is made more precise, then the shift is reduced, but the manufacturing complexity and cost increase
Solution Approach 1:
The bush is an intermediary element that compensates for manufacturing tolerances and alignment shifts without requiring ultra-precise manufacturing. The compliant polymer portion of the bush allows for slight misalignments while maintaining functional integrity, thereby reducing the stringency of manufacturing precision requirements and simplifying the overall assembly process while ensuring reliable operation.
Solution Approach 2:
The bush changes the operational parameters at the pin-central body interface by providing a compliant, shock-absorbing interface. This allows the system to function reliably with standard manufacturing tolerances rather than requiring ultra-precise alignment, thereby reducing manufacturing complexity and cost while maintaining adequate precision for proper operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The bush significantly extends the pin's lifespan by reducing friction and mechanical stresses, preventing premature breakage, and allowing operation under poor lubrication conditions, while also reducing noise and eliminating the need for expensive mechanical or thermal treatments.
Implementation Method 1
A bush with a bimetallic contact portion and an anti-friction coating is inserted between the pin and the seat, providing low friction
Implementation Method 2
damping vibrations, and allowing slight movements to absorb mechanical stresses
Data Source
AI summary
A bent axis pump wherein the coupling between a cylinder body and a connecting pin of a back body takes place by the interposition of a bush suitable for guiding the rotation of the cylinder body limiting the friction between the cylinder body and the pin. The pin life is considerably extended.